Human Stem Cell Research: Promises and Perils, Part 5
Posted by drbob2 on Jan 26, 2009
As I noted last time, when it comes to advances in ethical (non-embryonic) stem cell research, it’s hard to know when to stop gathering information and start writing. A fascinating report just recently came along from Europe that put together a multinational and multispecialty medical team that used ethical adult stem cell research to successfully treat a young Spanish woman with a serious lung condition. More about that below. In this, my last planned entry for this series on stem cell research, I will take note of:
- The use of the ethical Induced Pluripotent Stem Cells (iPSC) created in late 2007 to treat sickle cell anemia—so far only in mice;
- How a 2003 prediction for taking regenerative medicine beyond growing and modifying adult stem cells outside a patient’s body is being fulfilled; and
- The successful treatment of a Spanish woman using a multi-national team which used the patient’s own adult stem cells to tissue-engineer a segment of airway and then successfully transplanted it to replace her narrowed bronchus.
On November 20, 2007, the same day that Dr. Yamanaka reported his success in creating imps cells from a woman’s skin cell—which provided an amazing new tool for researchers to use, researchers also reported not only that they had duplicated Dr. Yamanaka’s experiment and produced iPS cells, but they had used them to successfully treat—in mice—sickle cell anemia.
This complicated but effective process is explained at Sickle Cell Mice Cure
As a reader of this series on stem cell research knows, the advances in ethical adult and IPS stem cell research involve a process like this:
- Take adult stem cells from a patient’s bone marrow, brain, fat, skin, or other source;
- Grow and multiply them by cell culture in the laboratory;
- Use the right “recipe” of growth factors, culture media, and other substances to get the adult stem cells to change into just the type of cell the patient needs;
- Then find a way to put them back into the patient, right where they are needed; and
- See if they will regenerate needed tissue and restore lost or diminished function.
That’s what is being done right now with adult stem cells already in treating human patients with heart disease, Parkinson’s disease, and some spinal cord injuries. It has been a useful process, and has even more promise, witness the enhanced possibilities of ethical research and human treatments using Induced Pluripotent Stem Cells.
Yet over five years ago, Dr. James Prentice, an ethical stem cell researcher and member of President Bush’s Commission on Bioethics, recognized that, although the process was effective and promised to be even more so, there may be a better way. As Dr. Prentice’s testified at before the President’s Commission on Bioethics in 2003:
“…perhaps the best avenue eventually to pursue might be trying to isolate what these factors are (which deliver a signal to the stem cells in a patient and stimulate them) so that no stem cells would be needed at all. Instead, if you can identify those factors to stimulate regeneration within the tissue, they could be delivered directly.”
In other words, instead of finding, removing, culturing, differentiating, and reinjecting our own reparative or regenerative stem cells, Dr. Prentice predicted it would be much simpler to identify the specific growth factors needed and then give them to patients to activate their own stem cells—right where they are— to change into the type of cells needed to repair or regenerate a diseased or destroyed organ or tissue.
Working with mice, Harvard’s Dr. Douglas Melton reported (August of 2008),that his team had done just that; injected a selected set of growth factors incorporated into a virus into diabetic mice. The virus contained three growth factor genes: Ngn2, Pdx1, and Mafa. The pancreas contains many kinds of cells but the two cells of interest here are the exocrinecells—which secrete essential digestive enzymes like pepsin and trypsin into the intestinal tract and endocrine cells, like the beta cells which secrete insulin into the bloodstream. Three days after the growth factor genes were injected into the pancreas’s of diabetic mice, 20% of the exocrine cells changed (without becoming stem cells first) directly into insulin-producing beta cells. Although the new cells did behave like ordinary beta cells, secreting insulin in response to rising glucose levels in the mice which did lower the glucose level, they remained as single or clumped cells and did not organize themselves into little islands in the pancreas the way ordinary beta cells do and did not appear to communicate with other beta cells as ordinary beta cells do. Even so, if this process can be safely translated into treating humans, it has tremendous significance.
The Cleveland Clinic is currently investigating the approach predicted by Dr. Prentice in human patients who have had a heart attack. First, they give patients growth factors to stimulate their production of adult stem cells. Then they give the patients a migration factor to see if they can induce the stem cells to migrate to the damaged heart muscle in hopes of repairing it. Even today that sounds like science fiction or something out of one of the Star Trek series.
A different and significant approach to treating humans with adult stem cells was recently announced. A multinational team of clinical researchers reported, in The Lancet, Early Online Publication, 19 November 2008, that they had successfully transplanted a hybrid section of a bronchus (breathing tube) into a 30 year mother of two. Mrs. Claudia Lorena Castillo Sanchez.
Mrs. Castillo-Sanchez, who lives in Barcelona, developed an unusual complication of pulmonary tuberculosis. The TB bacilli infected her left mainstem bronchus, the major airway which carries all the air from her trachea to her left lung. As a result of the infection, the cartilage in the wall of the bronchus, which keeps the airway open when we exhale, softened to such a degree that her airway became very narrow. Her doctors first inserted a stent to widen the narrowing but it was not successful and she became too short of breath to carry out her normal daily activities. To treat her, her doctors were considering removing her entire left lung.
In a remarkable multinational collaboration teams from Spain, Britain, and Italy carried out a treatment plan which involved “autologous tissue engineering.” As Dr. Paolo Macchiarini reported in The Lancet, the process began by taking a three inch segment of bronchus from an organ donor, who had died of a cerebral hemorrhage; removing all the donor’s immunologically active cells and then covering the outside of the graft with cartilage cells derived from Mrs. Castillo’s own bone marrow and replacing the inner lining of the graft with Mrs. Castillo’s own bronchial lining cells.
Surgeons then operated and took out the narrowed airway and replaced it with the donor’s “bioengineered” normal size bronchus. Her operation, in June of 2008 was successful and, so far, measurements of her lung functions have gone from 55% and 62% to 100% without any sign of rejection or other problems!
At this rate of progress, who knows what good things will have happened by the next time I pick up this subject,
We live in especially interesting medical times for a number of reasons, one being the recent recognition that each one of us is a virtual walking warehouse of adult stem cells that, with the application of proper techniques, can repair and regenerate diseases and conditions for which other treatments have been ineffective. When we add to the current successes being made with adult stem cells the additional promise of induced Pluripotent Stem Cells, the ethical reader and ethical researcher must wonder why anyone persists in killing little embryonic human beings in the name of “science.”
Remember, if you have a topic you’d like me to address, just send me an email at drbob@superhealthms.com.